The world is divided into four kingdoms, each representing an element, and the Avatar, a spiritual link to the elements, maintains balance. When the Avatar disappears, the Fire Nation attacks the Air Nomads to prevent interference with their plans for domination.

The Last Airbender
The protagonist, a youthful Avatar, embarks on a vital quest to harness the powers of the four elements and free the Water Tribes and Earth Kingdom from the Fire Nation's tyrannical rule.